UTF-8 Header within HTMLEditor POPUP - where is the code?

When you are within a host's filemanager, and use choose to edit an HTML file using the "HTML Editor" (WYSIWYG), where is the HTML generated for its headers?

I have attempted to change all instances of "UTF-8" to "ISO-8859-1" within:
1) /home/myhost/public_html/Wysiwyg/editor_files/editor_class.php
2) /usr/local/cpanel/3rdparty/WysiwygPro/editor_files/editor_class.php
3) Any I could find within /usr/local/cpanel/base/frontend/x/files